Oil psi dropping after 4k rpm?

[dtowngoalie]

I have an rb20 in my s13, runs pretty good but my oil pressure is concerning me. I have 50 psi at cold start at 1000 rpm , 20 psi at hot idle at 900rpm, and 40 psi at 2.5k. The 40 psi hold until about 4k, but after that I take her up to about 7k and she drops down to about 28 psi. This happens under all load conditions. (neutral, accelerating, wot, and decel. When I decel from 6k rpm to 4k rpm, my oil pressure actually goes up.I have a small dent in my pan by the drain bolt, but I know the pickup is on the other side of that. It dent kinda slants over to where the pickup is though. Id say exactly where the pickup is, theres a half inch dent. My question for you guys is do you think this dent is causing this because the dent is restricting flow at higher rpms, or do you think I just have an old worn out oil pump... or, god forbid, something else wrong . Let me know what you boys think

[virus77]

Oil pump is very possible, pull off the front cover and oil pump and check her out. Don't drive the car, especially not at 7k, you're gonna make a $150 issue alot bigger.

[dtowngoalie]

Yea I haven't been since I, only twice to verify it was consistant. But don't you think if the oil pump was worn, it would just pump 40 psi to redline? That's the only thing that doesn't make much sense to me.

[mattblancarte]

Not necessarily, it may have lost efficiency above 4k rpm due to a fan warping or something.

Remove the cover, as virus77 advised.

[virus77]

Also ive seen oil pickup tubes so clogged with debris on the mesh that you couldn't see daylight through it.... pull the pan while you are at it.